Kawasaki disease (KD) is a systemic vasculitis of unknown etiology. Although Kawasaki disease is the most common cause of acquired pediatric heart disease in the developed world, and remains a major medical problem because its signs and symptoms mimic many other childhood febrile illnesses. The absence of definitive diagnostic markers limits the accuracy of clinical evaluations of suspected KD with significant increases in morbidity. In turn, incomplete understanding of its molecular pathogenesis hinders the identification of rational targets needed to improve therapy.